Frequency hopping communication is also referred to as spread spectrum communication. In this method of communication the carrier frequency of a transmitter and the local frequency of a receiver of the same system hop in unison among respective preselected populations of frequencies. In each case, the frequencies are equally spaced between the limits of a selected band. The frequency hopping period is constant. At both transmitter and receiver, the hopping is controlled to follow a predetermined random program. The program repeats after a period measured in hours, days or months. Synchronizing methods known heretofore are inadequate.
It is an object of this invention to provide a method and means for synchronizing a receiver of a frequency hopping system with a transmitter of the system very rapidly at the beginning of a transmitted message without disturbing the transmitter.